User`s manual

4.4 Flash ROM (System ROM)
Figure 4–3 ISA Devices
LJ04141A.AI5
PCI-to-ISA
Bridge
82378ZB
PCI Bus
ISA
Slot
0
Combo
Chip
87312
Transceiver
ISA
Slot
1
ISA
Slot
2
TOY
1287
Keyboard/
Mouse
8242
sa<18:0>sa<9:0>
sa<19:0>
sa<2>
sd<7:0>
la<23:17>
sd<15:0>
ubus<7:0>
Diskette J30
Parallel J28
Comm 1 J29
Comm 2 J23
IDE J24
flash_adr19
J16 J17 J18
Flash ROM
1M x 8
86.5%
4.4 Flash ROM (System ROM)
The flash ROM, sometimes called the system ROM, is a 1MB, nonvolatile,
writable ROM. After the SROM code initializes the Alpha PCI 64–275 board,
flash ROM code prepares the board for booting. The flash ROM headers,
structure, and access methods are described here.
4.4.1 Special Flash ROM Headers
The header informs the SROM where to load the image, and whether or not
it has been compressed. The SROM allows the flash ROM to contain several
different ROM images, each with its own header. The header is optional for
flash ROM containing a single image. If the header does not exist, the 1MB
flash ROM is loaded and executed at physical address zero. Figure 4–5 shows
the header content.
4–6 Functional Elements